The invention provides a router with an antenna built in and a middle frame structure thereof. The router with the antenna built in comprises a first shell, a second shell, a printed circuit board (PCB), an antenna, a light guide column, and a middle frame structure, wherein the antenna is installed in the middle frame structure, the antenna is coupled with the PCB, the first shell and the secondshell enclose to form an accommodation cavity, the outer side wall of the accommodation cavity is an arc, the middle frame structure, the antenna, the light guide column and the PCB are all accommodated in the accommodation cavity, the first shell and the second shell are connected with the middle frame structure separately, a splicing seam is formed between the first shell and the second shell, the peripheral wall of the light guide column props against the inner side wall of the accommodation cavity and is exposed out of the splicing seam, a ribbon-shaped light source is arranged on the surface, close to the annular light guide column, of the PCB in an annular manner, and the ribbon-shaped light source faces the light guide column. Through adoption of router with the antenna built in andthe middle frame structure thereof, the antenna is arranged in the router in diversified manners, the internal structure of the side, close to the accommodation cavity, of the two shells is simplified, a mold structure processing the shell is simplified, so that the router shell is easier to process and realize.